What Is a Sound Level Meter?

Sound level meter is the most basic noise measuring instrument. It is an electronic instrument, but it is different from objective electronic instruments such as voltmeters. When the acoustic signal is converted into an electric signal, the time characteristics of the human ear's response to sound waves can be simulated; the frequency characteristics with different sensitivity to high and low frequencies, and the intensity characteristics of changing frequency characteristics with different loudness. Sound level meter is a subjective electronic instrument.

According to the sensitivity of the sound level meter, there are two methods for classifying the sound level meter: one is the ordinary sound level meter, which does not require high microphones. The dynamic range and the frequency response are relatively narrow. Generally, band-pass filters are not used in combination. The other is a precision sound level meter. The microphone requires a wide frequency response, high sensitivity, good long-term stability, and can be used with various sensors. This kind of band-pass filter is used together, the output of the amplifier can be directly connected with the level recorder,

The microphone converts the sound into an electrical signal, and the preamplifier changes the impedance to match the microphone with the attenuator. The amplifier applies the output signal to

Whether the sound level meter is used correctly or not directly affects the accuracy of the measurement results. Therefore, it is necessary to introduce the use of sound level meters.

1. Choice of sound level meter environment: Select a representative test location. The sound level meter should leave the ground and away from the wall to reduce the additional impact of the reflected sound from the ground and the wall.

2. Weather conditions require the sound level meter to keep the diaphragm of the microphone clean during rainless and snowless hours. Wind hoods must be installed above the third level (to avoid wind noise interference), and high winds above the fifth level should stop measuring.

3. Open the sound level meter carrying case, take out the sound level meter, and put on the sensor.

4. Put the sound level meter in the A state, check the battery, and then calibrate the sound level meter.

5, the comparison table (common reference of common ambient sound level size), adjust the measurement range.

6. The following can be used fast (measure the instantaneous value of the environment where the sound pressure level changes a lot), slow (measure the average value in the environment where the sound pressure level changes little), pulse (measure the pulse sound source), filter ( Measure the sound level of the specified frequency band) Various functions for measurement.

7. Record the data as required, and you can also connect to a printer or other computer terminal for automatic collection. Organize equipment and return to designated place. ^[1]

(1) Keep the exterior of the instrument clean;

(2) The microphone should be stored dry when not in use;

(3) The diaphragm of the microphone shall be kept clean and shall not be touched by hand;

(4) When the instrument is not used for a long time, it should be powered on for 2h every month, and it should be powered on for 2h every week during the rainy season;

(5) Take out the battery in time when the instrument is used;

(6) Regularly sent to the metrology department for verification. ^[2]

GB / T 3785.1-2010 Electroacoustic sound level meter Part 1: Specification.

GB / T 3785.2-2010 Electroacoustic sound level meter Part 2: Type evaluation test.

JJG 188-2002 sound level meter verification procedures.

GB / T 17312-1998 random incident and diffusion field calibration of sound level meter.

JJG 778-2005 Noise Statistics Analyzer.

SJ / T 10114-1991HS5633 digital sound level meter.

SJ / T 10423-1993 General technical requirements for sound level meters. ^[2]

Precautions

1) Please read the instruction manual before using to understand the use method and precautions of the instrument.

2) The instrument should be kept away from high temperature, humidity, sewage, dust and air or chemical gas containing hydrochloric acid and alkali.

3) Pay attention to the polarity when installing the battery or external power supply. The battery should be removed for a long period of time, so as to avoid damage to the instrument due to leakage.

4) Do not disassemble the microphone to prevent it from being dropped, and place it properly when not in use.

5) Do not disassemble the instrument without permission. If the instrument is abnormal, it can be sent to the repair unit or factory for repair.

6) During use, an undervoltage alarm appears in the LCD, and the battery should be replaced in a timely manner.

7) Before measuring the sound level meter, it can be preheated for 2 minutes, and 5 to 10 minutes on wet days.

Calibration of sensitivity

To ensure the accuracy of the measurement, calibration should be performed before and after use.

Combine the sound level calibrator with the microphone, turn on the calibration power, read the value, adjust the noise meter sensitivity potentiometer, and complete the calibration.

Measurement methods

When measuring, the instrument should choose the correct gear according to the situation. Hold the noise meter on both sides with both hands, and the microphone points at the sound source to be measured. You can also use extension cables and extension rods to reduce the appearance of the noise meter and the influence of the human body on the measurement. The position of the microphone shall be determined in accordance with relevant regulations. ^[2]

Sound level meter is the most basic instrument for measuring noise. It belongs to an electronic instrument. Sound level meter is generally composed of condenser microphone, preamplifier, attenuator, amplifier, frequency weighting network and effective value indicator. According to the sensitivity of the sound level meter, it can be divided into two categories, one is an ordinary sound level meter; the other is a precision sound level meter. According to the purpose of the sound level meter, it can also be divided into two categories: one is for measuring stability. State noise; one is used to measure unstable noise and impulsive noise.

The sound level meter uses advanced digital detection technology, which greatly improves the stability and reliability of the instrument. The sound level meter has the advantages of simple operation and convenient use; it has the characteristics of large dynamic range, large-screen LCD digital display, automatic measurement and storage of various data, and so on.

Sound level meters can be widely used in industrial noise measurement and environmental noise measurement of various machines, vehicles, ships, appliances, etc., suitable for factories and enterprises, architectural design, environmental protection, labor health, transportation, teaching, medical health, scientific research and other departments Field of acoustic testing. ^[2]